Simplified circuit breaker device with manual on-off control and manual reset



April 1968 H. R. SHAFFER ETAL 3,379,843

SIMPLIFIED CIRCUIT BREAKER DEVICE WITH MANUAL ON-OFF CONTROL AND MANUAL RESET Filed Sept. 7, 1966 5 Sheets-Sheet 1 N VENT OR: How/12o A. aw/Fae A ril 23, 1968 H. R. SHAFFER ETAL 3,3

SIMPLIFIED CIRCUIT BREAKER DEVICE WITH MANUAL ON-OFF CONTROL AND MANUAL RESET Filed Sept. 7, 1966 3 Sheets-Sheet 2 J I Jr 25-. 6.

Aprzi 23, 1968 H. R. SHAFFER ETAL 3,379,843

SIMPLIFIED CIRCUIT BREAKER DEVICE WITH MANUAL ON-OFF CONTROL. AND MANUAL RESET Filed Sept. 7, 1966 5 Sheets-Sheet 5 Jada /0aa0 -e 77/145 0,4,2; .5. eyczx o BY United States Patent 3,379,843 SIMPLIFIED CIRCUIT BREAKER DEVICE WITH MASNUAL (IN-OFF CONTROL AND MANUAL RE ET Howard R. Shaffer, Glenside, Pa, and Carl E. Gryctko, Haddon Heights, N.J., assignors to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Sept. 7, 1966, Ser. No. 577,772 5 Claims. (Cl. 200138) ABSTRACT OF THE DISCLOSURE A minimum number of inexpensive components are utilized to provide a compact circuit breaker device which includes a manual operator for moving between the contact ON and contact OFF positions, and an automatic trip means with reset being provided by the manual operator.

Our invention relates to circuit breaker devices of simplified construction and operation, and more particularly to such circuit breaker devices which may be made sufiiciently compact and low in cost to permit their installation in those applications previously utilizing replaceable type cartridge fuses.

In the protection of electrical circuits from a short circuit or other overload conditions; it is the general practice to include a circuit protective device between the power source and the load. The circuit protective device is designed to respond to circuit conditions above a predetermined value, for automatically interrupting the current flow to the load. In many applications such protection is afforded by a fuse which will rupture when subjected to a current above its rated value. Once the fuse has operated to protect the circuit, it is destroyed and it is necessary to remove the fuse and replace it with another one. A much more desirable protective device is an automatic circuit breaker which will trip open responsive to predetermined overload conditions and interrupt the current flow. The circuit breaker device is not destroyed by its protective operation, as in the case of the fuse, but may then be reset (typically by a conveniently accessible manual operating handle) to provide subsequent circuit protection.

In the past, circuit breaker devices have generally been of such a size and of such costs as to generally restrict their utilization in numerous applications where only a limited expenditure is commercially practical; e.g., the protection of automotive accessories. Our invention, however, provides a circuit breaker device of such simplicity of operation, compactness of size and ease of fabrication that it may be economically utilized in those environments which previously have been generally restricted to the utilization of replaceable fuses.

.It is therefore seen that a basic concept of our invention resides in the provision of an automatic circuit breaker device of increased simplicity of operation, compactness of size and of reduced cost.

It is therefore a primary object of our invention to provide a circuit breaker device of a type and size which may be readily incorporated in those environments previ- .ously utilizing replaceable type fuses.

A further object of our invention is to provide such a circuit breaker device which may be readily substituted Within mounting base assemblies presently designed for the reception of replaceable type cartridge fuses.

The circuit breaker device of our invention is contained within a compact housing having a generally rectangular internal volume portion, including opposed sidewalls, a topwall and a bottomwall. A pair of stationary contacts are positioned along spaced locations of the bottomwall.

A combined bridging contact and actuator is provided by an elongated bimetallic element, which is operatively connected to a plunger translatable along a path towards and away from the bottomwall. A portion of the plunger extends outward of the topwall to provide a manual operating handle. A flat spring member, slightly longer than the distance between the sidewalls, has its opposed ends mounted in restraining recesses of the sidewalls in a manner arcing the spring about a center line passing through the sidewall recesses and restraining movement of the spring along its longitudinal length. The central portion of the spring is operatively connected to the plunger and the central portion of the bimetallic element. Overload responsive actuation of the circuit breaker is provided by deflection of the bimetallic element, responsive to predetermined current flow therethrough, such that the arc of the spring will be urged towards its opposed overcenter condition. The movement across the center line is a snap action, to provide rapid separation .of the contacts, thereby interrupting the current flow. Hence, there will be first and second operative positions of the spring, with the center of the are in opposed overcenter relationship with respect to its restrained end locations. The spring will act in a manner analogous to an overcenter toggle, to provide snap action of the plunger between a first operative condition where the bimetallic element provides bridging contact between the stationary contact pair, and a second operative position where the circuit breaker has interrupted the flow of current between the stationary contact pair.

In accordance with a further feature of one form of our invention, the external contacts of the circuit breaker are in the form of circular members, analogous to the ferrule end tips of a cartridge type fuse. Thus, the circuit breaker device may be inserted within spring clips of the type pro vided on mounting blocks for receiving cartridge type fuse members. To further simplify the assembly of our circuit breaker and hence reduce its costs, the housing may be formed of first and second complementary sections held together by the ferrule type contacts, thereby eliminating the utilization of rivets or similar type securing means, previously required in circuit breaker devices. Advantage- .ously, the ferrule ty-pe contacts may also have the circuit breaker stationary contacts integrally formed therewith, to further minimize the required number of parts.

In accordance with another aspect of the form of our invention using ferrule type contacts, it is desirable that once the circuit breaker device is inserted within the contact clips of the mounting, it be prevented from pivoting about the axis of the contact clips. This may be provided by a downward extension of the circuit breaker housing to provide interference for the tendency of the circuit breaker device to pivot about the terminal contact clip.

In accordance with another aspect of our invention, in those applications where it is desirable to provide ambient temperature compensation, this may be achieved by constructing the operating spring member of an appropriately thermally responsive bimetallic composition to achieve the desired degree of compensation.

It is therefore seen that another object of our invention is to provide a circuit breaker device, in which a bimetal serves as a combined actuator and bridging contact.

Still a further object of our invention is to provide a circuit breaker device, in Which a flat spring member retained at both both ends from moving longitudinally operates in the manner of an overcenter toggle to provide snap action of the movable contact means towards its cooperating stationary contact means.

Still another object of our invention is to provide a circuit breaker device, which includes ferrule type contacts for convenient plug-in mounting to fuse-type spring contact clips, and further includes means to prevent the pivoting of the circuit breaker about the axis of the spring ips.

These as well as other objects of our invention will become readily apparent upon a consideration of the following description and drawings in which:

FIG. 1 is an exploded perspective view of a circuit breaker device constructed in accordance with one form of our invention, and shown in conjunction with the spring contact clips and mounting base, which may receive same.

FIGS. 2, 3 and 4 are side elevation, plan and end views respectively of the circuit breaker device of FIG. 1, shown mounted in it operative condition.

FIG. 5 is a cross-sectional view along the line 5-5 of FIG. 4, looking in the direction of the arrows, with the mounting block deleted, and showing the circuit breaker in its OFF condition.

FIG. 6 is a cross-sectional view corresponding to FIG. 5, but showing the circuit breaker in the ON condition.

FIG. 7 shows the circuit breaker device of FIGS. 5 and 6, corresponding to an overload condition, in which the bimetallic actuator has deflected and the circuit breaker is about to trip.

' FIGS. 8, 9 and 10 are cross-sectional views, corresponding to FIGS. 5, 6 and 7 respectively, but illustrating a modified form of our invention.

FIGS. 11 and 12 are side elevational and end views respectively of a further form of our invention which includes combined arc chutes and auxiliary housing retainers.

FIG. 12 shows a typical inverse-time characteristic, which has been demonstrated by circuit breakers of the instant invention.

Referring initially to FIGS. 1-7, circuit breaker device 10 is enclosed within a housing including complementary housing sections 12 and 14. The housing includes an internal volume, having first and second sidewalls 16, 18 respectively, a topwall 20 and a bottomwall 22. First and second stationary contact means 24, 26 are positioned at space locations along the bottomwall 22.

Electrically connected to the stationary contact means are external contact means 28, 30, which, in the form shown in FIGS. 1-5, are of a generally circular configuration, of a size analogous to the ferrule ends of conventionally available cartridge type fuse devices. External contact members 28, 30 tightly engage extensions 29, 31 of the housing, and in accordance with a particularly advantageous aspect of this form of our invention, may serve as the sole or principal retaining means for maintaining complementary housing sections 12, 14 in their abutting relationship.

The circuit breaker device 10 may be readily plug-in inserted within conventional type spring contact members 32, 34 mounted to base 36 and having screw-type contacts 38, 40 for receiving the leads (not shown) to the external circuit being protected by the circuit breaker 10.

Circuit breaker stationary contact pair 24, 26 are of the bridging variety; that is, when an electrically conductive path is provided therebetween, a circuit will be provided through the circuit breaker device 10 intermediate external contact means 28, 30. This bridging type contact is provided by the combined contact member and actuator 50, which is a bimetallic element. Bimetallic element is operatively connected to a first portion 52 of a plunger 60, such that as the first portion moves towards the bottom wall 22, contact engagement will be made by the ends 54, 56 of the bimetallic element 50, with stationary contacts 24, 26 respectively. End section 62 of the plunger 60 rides within guide slot 70 to provide vertically reciprocable movement.

A planar spring member 72 is mounted at its opposed ends 74, 76 within notched recesses 75, 77 of th housing side walls 16, 18 respectively for receiving Said SPTmg member 72 and restraining it against longitudinal movement. The central portion of the spring member is operatively connected to a second portion 53 of the plunger 60. Spring member 72 is of a length greater than the distance between side wall notches 75, 77, and hence will define an are about center line 100. Spring 72 may be actuated between opposed overcenter positions as shown in FIGS. 5 and 6 respectively. In FIG. 6, the plunger rod 60 has been moved downward, such that the bimetallic element 50 provides bridging contact between stationary contact means 24, 26, and current flow is provided therethrough. Responsive to predetermined overload conditions, in accordance with the thermal calibration of bimetallic element 72, the bimetallic element will beginito distortively deflect, as shown in FIG. 7, such that the plunger rod 60 is gradually urged upward. When the point is reached that the spring moves past its overcenter position, there will be a rapid snap action, in the manner of an overcenter toggle structure, such that the contacts are rapidly disengaged to the condition of FIG. 5. The breaker will then remain in the disengaged position until manually reset by the pressing downward of plunger 60. Where desired, spring member 72 may be constructed of a bimetallic element to provide suitable compensation for ambient conditions.

In accordance with another aspect of the form of our invention shown in FIGS. 1-7, a downward housing extension is provided to abuttingly engage the top surface of the terminal clip mounting block 36 and thereby prevent pivoting of the circuit breaker 10 about the axis Of terminal clips 32, 34.

Reference is now made to FIGS. 8, 9 and 10, which show a modified form of our invention, in the operating positions corresponding to FIGS. 5, 6 and 7, respectively.

The form of the circuit breaker shown in FIGS. 8, 9 and 10 is basically similar to that previously discussed, with the exception that the plung-in type ferrul contacts have been replaced with contact members 28, 30 respectively, including screw-type members 28" and 30" for receiving the connections to the external circuit being protected. The other elements of the circuit breaker device 10', which correspond in function to those shown in the previously discussed embodiments of FIGS. 1-7, are indicated by the same numerals but with prime designations, to readily permit their comparison.

FIGURES 11 and 12 show another modification of our invention, of particular utility for interrupting higher current magnitudes. U-shaped arc chute members are provided, having openings 117 to expel the gases generated during circuit interruption. Advantageously, arc chute members 115 are frictionally restrained by the walls of complementary cut-outs of the housing sections 12, 14, to serve as a further means for maintaining the housing sections together.

FIGURE 13 shows a plot 120 of typical inverse-time characteristics which have been obtained with a circuit breaker according to our invention, with both the time 122 and current 124 parameters being indicated on a logarithmic scale.

It is therefore seen that our invention provides an extremely simple circuit breaker device of small size, providing a double break relationship between the stationary movable contacts, with snap action being achieved by a single fiat-type spring member. Further, the circuit breaker and its external contacts may be made of a suitable size and configuration so as to be readily utilized in those environments previously restricted because of cost or size limitations to the use of replaceable type fuses.

Although there have been described preferred embodiments of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited not by the specific disclosure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A circuit breaker comprising: a housing having an internal volume including first and said movable contact means including an elongated bimetallic element deflecting responsive to a pre determined current fiow therethrough for moving said spring member in a direction such that said spring second sidewalls, a topwall and a bottom wall; 5 member is caused to move between its first and secfirst and second stationary contact means positioned ond operative positions for automatically moving at spaced locations along said bottom wall; said movable contact means to the contact OFF posicircuit breaker operating means for providing stable tion and interrupting the current flow between said ON, manual OFF and TRIP positions, and a manual stationary and movable contact means, the bimetal reset means for moving between the TRIP and ON 10 thereafter cooling and said spring member remainpositions, said operating means including: ing in said second operative position for maintaining a movable contact means for electrically bridging bethe contact OFF position until manually reset by tween said stationary contact means; said manual operator means.

a plunger having a first portion within said internal 2. In a circuit breaker as set forth in claim 1:

volume and a second portion external of said hous- 5 means in said sidewalls for receiving the spring ends ing to provide a manual operator means for manual and restraining movement of the spring along its reset and movement to the manual OFF position; length;

said plunger first portion translatable along a path for said spring member being substantially planar, and of moving the interior end thereof towards and away a length greater than the distance between said housfrom said bottom wall; ing sidewalls spring end receiving means;

a longitudinal spring member having a length substansaid intermediate region of said spring positioned betially in excess of its width; tween said spring ends and said bottom wall when first and second longitudinal ends of said spring member in said first operative position, and positioned bemounted to said first and second sidewalls; tween said spring ends and topwall when in said secmeans for connecting an intermediate region of said 0nd operative position.

spring member and said movable contact means to 3. In a circuit breaker as set forth in claim 2: said plunger first portion; said'spring when moving between its first and secsaid spring member having first and second operative ond operative positions rapidly passing through the positions, in opposed overcenter relationships with spring center to provide snap-action separation beresp'ect to its end locations; tween said stationary and movable contact means.

said first operative position corresponding to the interior 4. In a circuit breaker as set forth in claim 1:

endof said plunger positioned adjacent said bottom said spring member formed of a bimetallic material wall and said movable contact means bridging said and operatively related to the thermal characteristics stationary contact means to provide an electrically of said bimetallic element to provide ambient temconductive path therebetween and define the conperature compensation. tact ON position; 5. In a circuit breaker as set forth in claim 2:

and second operative position corresponding to the said spring member formed of a bimetallic material interior end of said plunger first end positioned away and operatively related to the thermal characteristics from said bottom wall and said movable contact of said bimetallic element to provide ambient temmeans gap-separated from said stationary contact perawre compensation, means to define the contact OFF position; References Cited said spnng member manually movable by said manual operator between said first and second operative posi- UNITED STATES PATENTS tions for manually moving said movable contact 1 7 5 9 5 1930 Thomas 200 13 X means between the contact ON and OFF positions; 2 22 1 9 12 1952 Cataldo et 1 00 13 X said spring member providing suificient force to main- 3 031 542 4 1962 Ellgnberger 200.416

tain said contacts in the selected one of said ON BERNARD A. GILHEANY, Primary Examiner.

R. COHRS, Assistant Examiner.

and OFF positions in the absence of an external manual input force; 

